Gelled elastomer compositions

ABSTRACT

Thickened elastomer compositions comprising a synthetic elastomer such as butyl or neoprene rubber, elastomeric solvent such as textile spirits and a di-substituted urea such as that formed by the in situ reaction of a long chain aliphatic amine and isocyanate, which are useful as rubber adhesives, sealants, and coatings.

United States Patent Inventors Appl. No. Filed Patented Assignee GELLEDELASTOMER COMPOSITIONS 16 Claims, No Drawings US. Cl 260/328 A, 252/316260/332 R, 260/336 A, 260/33.8 UA, 260/553 R, 260/553 A Int. Cl C08d9/00 Field of Search 252/316;

260/328 A, 553, 553 A, 33.6 A, 33.2 R, 33.8 UA

[56] References Cited UNITED STATES PATENTS 2,882,259 4/1959 Graham260/32.8 N 2,925,387 2/1960 Tralse et al. 260/553 A 3,242,210 3/1966Drehel' et al.... 260/553 3,350,342 10/1967 Begley 260/336 A 3,358,00512/1967 Garber et al.... 260/553 3,478,127 11/1969 Petersen 260/336 APrimary Examiner-Morris Liebman Assistant Examiner-H. H. Fletcher 1Attorney-Francis W. Young hesives, sealants, and coatings.

1 GELLED ELASTOMER COMPOSITIONS Rubber and elastomer compositions, suchas those employing butyl rubber or neoprene, have been used in the pastas rubber adhesives, cements and sealants. Such compositions are widelyused for bonding flexible materials like paper, textiles, leather andrubber to rigid materials like metals, plastics and ceramic materials.One serious drawback of known compositions is that when applied tononhorizontal surfaces, the composition is of such a viscosity that itsags or runs. Another disadvantage is encountered when solvents such asmineral spirits are employed in the compositions. The solvents aregenerally quite volatile and change viscosity of the composition as thesolvent evaporates, thus requiring close control of the composition andits application.

This invention therefore is directed to compositions which overcome manyof the disadvantages experienced with prior art materials, including theabove objections. The invention provides compositions, which can be usedas coatings, adhesives,- cements, sealants, and the like, havingthixotropic properties. This is the characteristic of certain gels tobecome fluid or less viscous upon agitation and then return to theirnormal highly viscous condition upon standing. More specifically, thisinvention is directed toward thickened elastomer compositions comprisingsynthetic elastomer material, elastomeric solvent and a minor proportionof adi-substituted urea hereinafter called urea preferably such as thatformed by the in situ reaction of an amine and isocyanate.

Thus, it is an object of this invention to provide novel gelledsynthetic elastomer compositions which can be readily formulated underfield conditions to provide stable compositions of various viscosities.Another object is to provide elastomer compositions which can be appliedonto nonhorizontal surfaces without exhibiting sag. Still another objectis to provide elastomer compositions which form stable invert emulsionsin water. The thixotropic gelled synthetic elastomer composition of ourinvention comprises synthetic elastomer material, elastomeric solvent,and urea preferably produced by the in situ reaction of an aliphaticamine and an isocyanate selected from the group consisting of aromaticand aliphatic monoand polyisocyanates. Mixtures of amines and monoandpolyisocyanates can be used. The amine terminated structure ispreferred.

Aliphatic amino compounds are preferred amine reactants, especiallythose containing an aliphatic group of about 6 to 22 carbon atomsattached to an amino nitrogen. Such aliphatic groups may be branched orstraight hydrocarbon chain, saturated or olefinically unsaturated,cyclic, or aralkyl such as 9,l-phenylstearyl such as derived from oleicacid. Primary mono-amines are preferred; and N-secondary-alkyl aminesare particularly preferred due to their low melting points therebyproviding amines having fluid properties under field conditions, and dueto their characteristic of maintaining controllable viscosity in thecompositions of the invention. Such amines can be produced by amidationof olefins in hydrogen fluoride followed by conversion of the amide toamine. These amines are generally isomeric compositions with respect tothe attachment of nitrogen to the aliphatic chain, and are of chainlengths reflecting the olefin cut used as a reactant. Thesecondary-alkyl amines may be represented by the general formula;

wherein x and y are integers having a sum from about three to l9. Apreferred subclass is N-secondary-alkyl amines that are mixtures ofhydrocarbon chain lengths having from about six to 22 carbon atoms.Amines of this class are commercially available in chain lengths of C CC and C (AR- MEEN primary Beta-amines, Armour Industrial ChemicalCompany). Mixtures of the foregoing amines may be employed.

isocyanates suitable for employment in this invention include thoseisocyanates that react with an amine to form urea. Long chain aliphaticisocyanates wherein the aliphatic group contains from about six to 22carbon atoms are desirable. It is preferred to use difunctionalisocyanates, or prepolymers thereof, selected from the group consistingof aromatic diisocyanates such as toluene diisocyanate, aliphaticdiisocyanates such as hexamethylene diisocyanate and the long chainaliphatic diisocyanates such as are derived from aminostearylamine andaminomethylstearylamine. Toluene diisocyanate is particularly preferredin forming the compositions, and commercial toluene diisocyanate whichis generally a mixture of tolyl 2,4- and 2,6- has been used withexcellent results.

Suitable compositions according to the invention may be formulated usingminor amounts of urea, and from about 2 to 10 weight percent urea formedin situ from the amine and isocyanate is preferred. Urea may simply beadded to the elastomer and elastomeric solvent. Especially preferablecompositions contain from 4 to 8 weight percent urea. The optimumconcentration of urea will vary depending upon the type of elastomermaterial and solvent utilized, and the particular thickening propertiesdesired. For example, at lower concentrations of urea the productsgenerally exhibit soft, firm gels. At the higher concentrations of urea,the products generally form hard, firm gels.

Elastomers suitable for use in this invention include those elastomershaving the properties of natural, reclaimed, vulcanized or syntheticrubber. One preferred subclass is synthetic elastomers produced bypolymerization of butadiene alone or with isobutylene. Copolymers ofbutadiene and isobutylene, formerly known as butyl rubber and now alsoknown as GR-l, are preferred. Another preferred subclass is thesynthetic elastomers produced by polymerization of chloroprene.Chloroprene polymers by the polymerization of 2-chloro-l,3-butadienemade by the reaction of hydrogen chloride on monovinylacetate areespecially preferred. Such copolymers are known as neoprene and alsotermed GR-M.

A wide variety of organic elastomer solvents are suitable for use in thecompositions of this invention including petroleum distillates,kerosene, fuel oils, mineral spirits, gasoline, turpentine, textilespirits, naphtha, benzene, toluene, carbon tetrachloride,methylisobutylketone, methyl-Cellosolve (ethylene glycol monomethylether) and the like. The choice of a particular solvent is dependentupon the rate of cure desired and nature of elastomer material utilized.For example, more volatile solvents are selected for rapid vulcanizationproperties. A particularly preferred solvent is textile spirits. Thecompositions of the invention may contain from about 30 to weightpercent of solvent materials and from about 40 to 60 percent ispreferred.

The gelled synthetic elastomer-cutback compositions may also containother additives that do not interfere with urea forming reactions, suchas wetting agents and additional adhesion agents.

The compositions of this invention may be readily formulated fromelastomer-cutbacks well known in the art to be made by addition ofsolvent to elastomer material with mixing. The thixotropic compositionscan be formulated by simply adding urea or by mixing of the amine andisocyanate reactants in the elastomer-cutback composition to form ureain situ. In the latter mode, it is preferred to add the amine first andthen add the isocyanate with stirring. in forming the urea, it issuitable to use from the stoichiometric requirement of amine andisocyanate to about 40 percent excess of amine. That is, the mole rationof amine to diisocyanate for example may range from about 2:1 to 2.811.The compositions of the invention may be formulated in batches by simplemixing in tanks, and stored for use as desired. Such compositions arestable over long periods of time. They may also be formulated on acontinuous basis, such as may be desired in spraying applications, byintroducing appropriate quantities of amine and isocyanate into theelastomer latex-solvent flow in a pipe leading to the spray nozzle.

The compositions may be applied directly by spraying or caulking, or asinvert aqueous emulsions. The compositions form stable invert emulsionswhen about 8 to 10 weight percent water is added. Such emulsions areespecially useful in adhesive and sealant applications.

The following specific examples are presented to further illustrate thisinvention, and are not to be construed in any way or manner as imposinglimitations upon the scope thereof.

EXAMPLE l 10 until maximum thickening was obtained. After aging for one20 week, the gels in each case had the appearance noted in table I andTable ll. The thickened synthetic elastomer compositions formulated inthis fashion exhibited good stability.

EXAMPLE ll Using a procedure as set forth in example i, 60 weightpercent butyl rubber was combined with 40 weight percent of textilespirits. Urea in situ was formed therein at 4 weight percentconcentration. The result was a stable thickened synthetic elastomer gelof medium firmness exhibiting good stability and excellent properties asa crack sealer.

While this invention has been described with respect to specificembodiments of thickened elastomer compositions and processes, it is notso limited. it is to be understood that variations and modificationsthereof obvious to those skilled in the art may be made withoutdeparting from the spirit or scope of this invention.

What is claimed is:

l. A thickened elastomer composition comprising; synthetic elastomerselected from the group consisting of butyl and neoprene rubbers; about30 to 95 weight percent of an organic solvent for said elastomer; andabout 2 to 10 weight percent of di-substituted urea produced by the insitu reaction of an aliphatic hydrocarbon primary monoamine anddiisocyanate selected from the group consisting of aromaticdiisocyanates ('IDI) MOLE RATIO 2:1

Total amine- TDI concen- Gel appearance tration, Time of Amino percentgelation Initial After aging N-soc-nlkyl (014) primary amine. gsecViscous slight gel Viscous slight gel.

Do sec o.

Soft firm gel.

H H H b- H PNPN. PNPN. 91 1M. PNPN. PNFN. cocomoooomocoocnoooomoooomFluid.

Slightly viscous fiuid.. Heavy viscous fluid.

5 min 811 htly viscous gel. Soft firm gel.

TABLE II.THICKENED ELAS'IOMER GELS AMINE-TOLUENE DIISOCYANATE ('IDI)MOLE RATIO 2.4:1

Total amine 'IDI concen- Gel appearance tration, Time of Amine percentgelation Initial After aging N-sec-alkyl (V 7-9) primary amine. 5Fltuitd ()white precipi- Fltuil (white precipia e. a 2. 0 5 min. Viscousfiuid Slightly viscous fluid. 4. 0 5 min Soft firm gel. Soft firm gel.7. 0 0 Do. 10. 0 D0.

5 Viscous gel 2. 0 Soft viscous gel. 4s 0 do Soft firm gel 7. 0 Do. 10.0 d Hard firm gel.

. 5 2. 0 5 min Soft firm gel Soft firm gel. 4. 0 5 Sec do Do. 7. 0 5 secdo. Do. Do 10. 0 5 sec do... Hard firm gel. N-sec-alkyl (Cu-n) primaryamine. 5 Fluid F D0 2. 0 Slightly viscous fluid.. Soft slight 381- Do.4. 0 Soft firm gel Soft firm gel. Do 7. 0 Do. Do. 10.0 Hard firm gel.N-cocoamine 5 Soft viscous gel. Do 2.0 Soft firm gel. Do 4. 0 D0. D0. 7.0 Hard firm gel. Do 10. 0 Do.

and aliphatic diisocyanates wherein the aliphatic group contains aboutsix to 22 carbon atoms, said amine added in the mole ratio of amine todiisocyanate of from 2:l to 2.8: l.

2. The composition of claim 1 wherein said amine has an aliphatic groupcontaining from six to 22 carbon atoms and is selected from the groupconsisting of branched and straight hydrocarbon chain, saturated andolefinically unsaturated, cyclic and aralkyl.

3. The composition of claim 2 wherein said amine is an N-secondary-alkyl amine having the general formula:

wherein x and y are integers having a sum from about three to 4. Thecomposition of claim 1 wherein said diisocyanate is toluenediisocyanate.

5. The composition of claim 1 wherein said monoamine has from six to 22carbon atoms and said diisocyanate is toluene diisocyanate.

6. The composition of claim 5, said amine being an N- secondary-alkylprimary amine.

7. The composition of claim 1 wherein said solvent is present in about40 to 60 weight percent.

8. The composition of claim 1 wherein said di-substituted urea ispresent in about 4 to 8 weight percent.

9. The composition of claim 1 wherein said solvent is selected from thegroup consisting of petroleum distillates, kerosene, fuel oils, mineralspirits, gasoline, turpentine, textile spirits, naphtha, benzene,toluene, carbon tetrachloride, methylisobutyl-ketone, and ethyleneglycol monomethyl ether.

10. A process for producing thickened elastomer compositions comprising;mixing synthetic elastomer selected from the group consisting of butyland neoprene rubbers with about 30 to 95 weight percent of an organicsolvent for said elastomer; and adding thereto an aliphatic hydrocarbonmonoamine and diisocyanate selected from the group consisting ofaromatic diisocyanates and aliphatic diisocyanates wherein the aliphaticgroup contains about six to 22 carbon atoms, said amine and diisocyanateadded in the mole ratio of from 2: l to 2.8: l to produce in situ about2 to 10 weight percent of di-substituted urea.

11. The process of claim 10, said solvent being selected from the groupconsisting of petroleum distillates, kerosene, fuel oils, mineralspirits, gasoline, turpentine, textile spirits, naphtha, benzene,toluene, carbon tetrachloride, methylisobutylketone, ethylene glycolmonomethyl ether.

12. The process of claim 10, said solvent being present in from -60weight percent.

13. The process of claim 10, said urea being present in from 4-8 weightpercent.

14. The process of claim 10, said amine being added with stirring, andthen said isocyanate being added with stirring.

15. The process of claim 10, said amine being an N-secondary-alkyl aminehaving the general formula:

wherein x and y are integers having a sum from about three to 16. Theprocess of claim 10 wherein said monoamine has from six to 22 carbonatoms and said diisocyanate is toluene diisocyanate.

2. The composition of claim 1 wherein said amine has an aliphatic groupcontaining from six to 22 carbon atoms and is selected from the groupconsisting of branched and straight hydrocarbon chain, saturated andolefinically unsaturated, cyclic and aralkyl.
 3. The composition ofclaim 2 wherein said amine is an N-secondary-alkyl amine having thegeneral formula:
 4. The composition of claim 1 wherein said diisocyanateis toluene diisocyanate.
 5. The composition of claim 1 wherein saidmonoamine has from six to 22 carbon atoms and said diisocyanate istoluene diisocyanate.
 6. The composition of claim 5, said amine being anN-secondary-alkyl primary amine.
 7. The composition of claim 1 whereinsaid solvent is present in about 40 to 60 weight percent.
 8. Thecomposition of claim 1 wherein said di-substituted urea is present inabout 4 to 8 weight percent.
 9. The composition of claim 1 wherein saidsolvent is selected from the group consisting of petroleum distillates,kerosene, fuel oils, mineral spirits, gasoline, turpentine, textilespirits, naphtha, benzene, toluene, carbon tetrachloride,methylisobutyl-ketone, and ethylene glycol monomethyl ether.
 10. Aprocess for producing thickened elastomer compositions comprising;mixing synthetic elastomer selected from the group consisting of butyland neoprene rubbers with about 30 to 95 weight percent of an organicsolvent for said elastomer; and adding thereto an aliphatic hydrocarbonmonoamine and diisocyanate selected from the group consisting ofaromatic diisocyanates and aliphatic diisocyanates wherein the aliphaticgroup contains about six to 22 carbon atoms, said amine and diisocyanateadded in the mole ratio of from 2:1 to 2.8:1 to produce in situ about 2to 10 weight percent of di-substituted urea.
 11. The process of claim10, said solvent being selected from the group consisting of petroleumdistillates, kerosene, fuel oils, mineral spirits, gasoline, turpentine,textile spirits, naphtha, benzene, toluene, carbon tetrachloride,methylisobutylketone, ethylene glycol monomethyl ether.
 12. The processof claim 10, said solvent being present in from 40-60 weight percent.13. The process of claim 10, said urea being present in from 4-8 weightpercent.
 14. The process of claim 10, said amine being added withstirring, and then said isocyanate being added with stirring.
 15. Theprocess of claim 10, said amine being an N-secondary-alkyl amine havingthe general formula:
 16. The process of claim 10 wherein said monoaminehas from six to 22 carbon atoms and said diisocyanate is toluenediisocyanate.